Volar DRUJ Instability in Distal Radius Malunion

Abstract Volar dislocation of the distal radioulnar joint (DRUJ) is rare and is frequently missed, especially when associated with distal radius malunion. Chronic or locked volar DRUJ instability presents substantial diagnostic and surgical challenges, and practical guidance in the literature remains limited. This study describes a case series of patients with malunited distal radius fractures and volar DRUJ instability and proposes a practical treatment approach based on residual joint mobility and chronicity. We retrospectively reviewed eight women with a mean age of 41.3 years who presented between 2021 and 2025 with volar DRUJ instability in the setting of distal radius malunion. Clinical findings, radiographs, and intraoperative assessment were used to classify cases as either flexible or locked dislocations. Patients with residual pronation underwent attempted closed or open reduction, whereas patients with fixed deformity underwent salvage procedures. Functional outcomes were assessed with the Modified Mayo Wrist Score (MMWS) and wrist/forearm range of motion. Two flexible DRUJ dislocations were treated successfully, one with closed reduction and plaster immobilization and one with open reduction and temporary pinning. Five locked dislocations required salvage procedures: Two Sauvé–Kapandji procedures, two Darrach procedures (one combined with distal radius osteotomy), and one Baldwin osteotomy. One additional patient with partial pronation did not undergo further intervention and was later lost to follow-up. Overall, two patients were lost to follow-up. Preoperatively, all patients had limited pronation. Among the remaining six patients, the mean follow-up was 11.2 months (range, 8–18 months), the mean supination was 81.7 degrees, and the mean pronation was 65 degrees. MMWS values ranged from 60 to 95. Outcomes were recorded as excellent in two patients, good in two, and fair in two. Radiographs in the followed patients showed maintained reduction without postoperative complications. Volar DRUJ instability associated with distal radius malunion requires a high index of suspicion and an individualized treatment strategy. Closed or open reduction may be effective in selected flexible cases, whereas chronic locked dislocations usually require salvage procedures to restore functional forearm rotation. Larger studies are needed before definitive treatment recommendations can be made. Therapeutic, Level IV.